1. Field of the Invention
The present invention relates to devices for stabilizing oil pipe casing. More particularly, the present invention relates to a casing stabilizer device for securing the head of an oil well casing during the drilling operations.
2. General Background and Prior Art
In the drilling of oil wells, it is critical that the well be drilled with utmost safety, yet with attempting to minimize the expense and time involved. At the present state of the art, the original bore of the well is drilled out to a shallow depth and an exterior casing pipe is inserted into the bore, the diameter of which ranges from approximately 135/8 inches up to 20 inches in diameter. The head of the casing is then secured with a blowout preventor so that the drilling out of the bore within that casing in order to accommodate the next smaller casing (hereinafter referred to as surface pipe) may be done so to a greater depth within the exterior casing bore and with a maximum of safety. This surface pipe will serve as a containment pipe for the actual drilling pipe for drilling the oil well itself. However, this surface pipe, also, must be secured with a blowout preventor apparatus so that when the oil well is actually drilled, the safety device is in place during the drilling operation.
In order to secure the surface pipe within the exterior casing, the present art involves the singular method of pouring liquid concrete into the space between the surface pipe and the exterior casing down the bore. The concrete is then allowed to at least partially dry (a process usually taking 12 to 18 hours) which, during this time, the oil well is shut down. Following the drying of the concrete, the surface pipe is then secure enough in place to be cut off a few feet from ground level, above the surface of the exterior casing, and the blowout preventor is then secured, usually through welding, onto the head of the surface pipe. The well then is now in readiness for the actual drilling operation to begin, the drill pipe and bit being lowered down into the interior of the surface pipe itself.
However, even with this method of securing the surface pipe, the surface pipe does not maintain stability. As the oil well itself is drilled, the impact and vibration of the drilling pipe as it rotates within the surface pipe bore during drilling, in effect, breaks up the concrete, the result being that the surface pipe becomes loose and increasingly unstable as the drilling goes to a greater depth.
At present, a second step is taken in the process, following the breaking of the concrete, which would involve pouring of an aggregate, such as for example, pea gravel into the space between the exterior casing and the surface pipe, in an effort to help stabilize the surface pipe by the pea gravel filling in the inter-concrete spaces and, hopefully, stabilizing the surface pipe enough to complete drilling of the well. This step also has shortcomings in that the pea gravel does not really stabilize the surface pipe and, in effect, simply serves as a buffer between the surface pipe and the exterior casing, often times resulting in the surface pipe being very unstable and the drilling operation having to slow down or even stop in order to restabilize the surface pipe within the exterior casing.